So since I got my 2500k and its running SO much better than my e2180 @ 3.6ghz, I'm thinking my next step is another 5850. However I'm curious if my power supply would suffice or if I should upgrade that first. Please note my power supply is the HX series, not a TX or some other cheaper series.

So I rounded up some reviews to get an idea of what they say power requirements are.

I would recommend a better power supply for sure. Atleast around 750+ watts. From what you said you are overclocking and looks like your interested in another GPU. You have to make sure your Psu is atleast 100-150W over the 100% tdp and 100% system load of your rig to supply clean power. When your computer gets older you will have to also account for capacitor aging which will consume more power. In conclusion, an 800-850watt power supply is ideal for your build especially if your doing CFX. The most accurate website I found to do power calculations is here http://extreme.outervision.com/psucalculatorlite.jsp
Hope this helped
P.S. Look for psu's with high amperage rails

I dont mind spending good money, honestly I am probably turning into a Corsair fan and my next PSU will be another Corsair. Probably a TX750, GS800, maybe the HX750 or an AX750. Ill go high end to ensure I can run crossfire/sli 2 generations from now as well.

Thanks for solidfying PSU is next. Unfortunately I dont think I want to use my Cm690 with a new PSU with more cables. So Ill be getting a case as well. lol